Two decades-old Chinese-style townhouses in Mid-Levels, owned by banker David Li Kwok-po and his uncles, have been demolished despite their grade two historic listing.

The owners are said to be planning to reassemble part of the facade of the building on a 25-storey apartment block they will build on the site - an approach heritage experts dismissed as 'decoration' rather than conservation.

A heap of rubble was all that was left of 6 and 8 Kennedy Road yesterday, as hoardings reading 'revitalising Hong Kong's old buildings' surrounded the site and construction workers transported the waste away.

Dr Ng Cho-nam, a member of the Antiquities Advisory Board, said he was surprised by the wholesale demolition, as he had expected the new building to take shape with the existing facade still in place.

'Even though the elements are now stored and will be reassembled, this is different from what we imagined. I thought the facade would be kept on site during reconstruction,' Ng said.

'Reassembling the facade does not equate to conservation. This is just decoration.'

A person familiar with the project said elements of the facade were being stored in a warehouse in Lau Fau Shan, Yuen Long.

The homes were built in 1927 and 1935 by Li Koon-chun, David Li's grandfather and a founder of the Bank of East Asia, for his family.

It is jointly owned by the companies of three of Li's sons, including former stock exchange chairman Ronald Li Fook-shiu, Li Fook-hing and Dr Simon Li Fook-sean, who ran in the first election for chief executive in 1996, and a company belonging to Li Koon-chun's grandsons, Bank of East Asia chairman David Li and his brother Arthur Li Kwok-cheung.

The family lived in the townhouses until the 1960s.

They first applied to build the apartment block and associated recreation facilities in 2010, and applied to the antiquities board for permission to downgrade the historic grading of the mansions to grade three, an application the antiquities board rejected.

Board members said the neoclassical architecture was a landmark and a reflection of the life of a well-to-do business family living in Mid-Levels in the past century.

But a grade two listing is not enough to prevent demolition, and plans for the new flats were approved by the Buildings Department last year, while heritage officials persuaded the owners to agree to preserve important features such as the facade

Dr Lee Ho-yin, a board member and director of the University of Hong Kong's architectural conservation programme, also criticised the idea of reassembling the facade.

'This is a common practice on the mainland, but rejected in places like Canada. Reassembly is not conservation,' Lee said. 'Either you keep it or you knock it down. It's hard to take the middle path in this case.'

A spokeswoman for the Bank of East Asia said David Li had no comment on the case.